CVE-2026-82217: CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in Eclipse Foundation Eclipse Theia

CVE-2026-82217 is a path traversal vulnerability (CWE-22) in Eclipse Theia's AI Agent Mode file-change tools (writeFileContent, suggestFileContent, and related helpers) in versions 1.73.0 up to but not including 1.75.0. The vulnerability arises because the tools resolve model-supplied file paths without enforcing workspace containment checks. An attacker can supply crafted relative paths (e.g., ../.bashrc), absolute paths, or ~-expanded paths to write or delete files outside the workspace with the privileges of the Theia backend OS user. Since the path argument can be influenced through indirect prompt injection and writes occur without confirmation dialogs, this can lead to writing to critical host files such as shell startup scripts or authorized SSH keys, enabling escalation to code execution on the backend system.

Successful exploitation allows an attacker to write or delete arbitrary files on the host system outside the intended workspace boundaries, using the privileges of the Theia backend OS user. This can lead to full code execution on the backend by modifying critical files such as shell startup scripts or SSH authorized keys. The vulnerability has a high severity score (CVSS 8.8) reflecting its potential for remote exploitation without privileges and significant confidentiality, integrity, and availability impact.

No explicit patch or fix is currently documented for this vulnerability. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should avoid enabling AI Agent Mode file-change tools or restrict their usage to trusted inputs only. Monitoring vendor channels for updates and applying official fixes once released is recommended.